The People's Liberation Army's Navy (PLAN) submarines cannot spot United States
satellites high overhead as the submarines leave their bases at Sanya on Hainan
Island, Qingdao in Shandong province and Ningbo in Zhejiang province, and head
for deeper water.

Plenty of very deep water can be found in the South China Sea, especially in the zone north of the Spratly Islands, east of the
Paracels, and south of the Luzon Strait.

"A more challenging area for submarines to operate undetected is the East China
Sea, which is quite shallow from the Chinese coastline up to the Okinawa Trough
with a depth of only 30 to 60 fathoms [180 to 360 feet] in most places," said
associate professor Peter Dutton with the China Maritime Studies Institute at
the US Naval War College.

"Much of the water space [in the South China Sea] is more than 2,000 fathoms
deep," said Dutton.

Detecting submarines via satellite is a form of Non-Acoustic Anti-Submarine
Warfare (NAASW). Lasers, infrared and other detectors and synthetic aperture
radar (SAR) in space may be used as part of this NAASW activity. Satellites
might see subtle undersea disturbances caused by submarines, watch wave
patterns on or beneath the sea surface, or detect subtle variations in ocean
temperature.

This is not to be confused with satellite communications, nor is an "EO" or
"Earth Observation" satellite to be confused with "EO" as in an
"Electro-Optical" means of detecting submarines.

Over the next 18 months, the US National Reconnaissance Office (NRO) - operator
of the US spy satellite fleet - is planning multiple satellite launches, and
China must assume that one or more of these new US surveillance satellites will
help support US Navy efforts to locate and track PLAN submarines.

Satellites form a network along with undersea sensors and detectors fixed on
the sea floor or drifting in the open ocean as well as devices mounted on other
submarines, ships, unmanned undersea vehicles (UUVs), aircraft, helicopters and
unmanned aerial vehicles (UAVs).

Many are skeptical that satellites can perform NAASW missions effectively,
reliably and at reasonable cost.

"The natural disturbances of the sea surface due to wind and tides, it seems to
me, are very likely to mask any disturbance due to a submarine passage, and so
even if this were a viable detection technique, it seems to me so limited in
application that it would not be worth the investment," said one former US Navy
sonar expert.

In April, a source told RIA Novosti, a Russian newspaper, that Russia had
developed a novel satellite module "used for both defense and civilian
purposes, in particular, providing meteorological data", and it can "carry out
remote sensing of the sea and detect submerged submarines". This will be tested
in space perhaps as early as next year. [1]

"Submarine detection, by any means, is a classified and highly guarded topic.
The fact that the Russians are talking about it is the most interesting aspect
of this announcement," said Brian Whitehouse, president of Nova Scotia-based
OEA Technologies, Inc. He co-authored a paper with Daniel Hutt in 2008 about
spaceborne sensors, ocean intelligence, and the maritime battlespace. [2]

The satellite in question is apparently the first of three small Russian
Kanopus (Konopus) remote sensing satellites.

"This satellite is planned for 2011 and it will carry an Earth observing
payload that includes a sensor for studying the underwater light environment,"
said Dr Jonathan McDowell, an astrophysicist at the Massachusetts-based
Harvard-Smithsonian Center for Astrophysics who is also the editor of
Jonathan's Space Report. "I cannot evaluate the claim that this will let them
detect the wakes of submarines. I do not believe that such technology is being
used operationally at the moment. I am not aware of relevant flight
experiments, but they may have occurred."

Russia has previously demonstrated its satellite sub-hunting skills. Swedish
satellite expert Sven Grahn identified the Russian Almaz-1 satellite which was
launched in 1991 as a submarine-detection satellite that could see the surface
wake or trail of a submerged sub. Besides this satellite, the Russians deployed
other large, nuclear-powered and radar-equipped ocean surveillance satellites.

"Russian satellites known as RORSATs used radar to track surface ships, but the
US Navy was not concerned that our subs could be detected, much less tracked.
The signals, even if they existed, would be so wrapped into random noise that
extracting any usable intelligence from them proved impossible," author James
Oberg, a top US expert on Soviet and Russian space programs, told Asia Times
Online. "The cancellation of that [Soviet] satellite program followed at least
three accidental re-entries of debris. The laws of physics compelled them to
orbit as low as possible, creating high air drag."

The theoretical boundary below which satellites cannot successfully maintain
their orbits is approximately 160 kilometers above the Earth.

The Soviet space station Mir may have served as a platform for related research
activities in the same way that the US Skylab once served as a platform for
space radar testing in 1970s.

In the late 1990s, sub-hunting satellites made headlines. An American
scientist, Peter Lee, was caught and convicted of passing sensitive information
to China about the so-called Radar Ocean Imaging (ROI) joint project which
involved the United K and the US. A decision by the US Navy based on concerns
about further disclosures about the nature and scope of the ROI project echoes
to this day.

"Peter Lee's case was they had this guy giving this very sensitive data to the
Chinese on underwater detection of submarines. They ran into this case where
the navy wouldn't allow a court case against him because of the data. So they
had a bargain plea, and he got off, basically. For stealing very high-level
stuff, he gets probably, what, a couple of months in a halfway house," former
US ambassador to China, James Lilley, told PBS in 2004. [3]

China obtained relevant information from Russia, too.

"Chinese experts reportedly received technical assistance from Russian
satellite experts in years following the Soviet Union's collapse," said
associate professor Andrew Erickson at the China Maritime Studies Institute.
"Specialists at the State Key Laboratory of Satellite Ocean Environmental
Dynamics have researched ship detection using [SAR]."

Maritime surveillance became a top priority at the national level when China's
so-called, "863 State High-Technology Development Plan" was activated. And
China's fleet of Haiyang ocean surveillance satellites will grow to three when
Haiyang-2A is launched later this year

Prior to the ROI program, the US SEASAT ocean satellite project which was
launched by the US National Aeronautics and Space Administration (NASA) in 1978
carried a SAR into space for maritime surveillance purposes. After just over
100 days in space, SEASAT suddenly stopped working due to a short circuit in
the design of its solar panels.

"Rumors suggested it had been turned off or sabotaged. There was a claim that
SEASAT had mapped a field of World War 2-era shipwrecks on the floor of the
English Channel," said Oberg.

A US Navy oceanographer from Australia, Paul Scully-Power, who became the first
oceanographer in space, flew on the space shuttle Challenger (STS - 41G) in
1984. The US Navy later admitted that the mission had successfully detected the
undersea or internal waves generated by a submarine which had been tracked
successfully at relatively shallow depths. This was deemed, "incredibly
important to us" and was reported by the Washington Post in 1985 - quoting a
senior US Navy admiral at the time. [4]